User Modeling In UCSD

User Model is a psychologically valid way of depicting the people who will use the systems, and whose needs and preferences will be considered when designing those systems; itshould be able to represent or in part their psychological processes, individual differences, social context, cultural factors and lifestyles, and task objectives.Types of User Model1. Psychological Theories as User ModelsThere are a number of powerful models to capture key parameters of system users. Such models require its users to be a Cognitive Psychologist; students and teachers find theminaccessible and intractable.2.-

Task Analysis and for User Models

Task based analysis. The evaluation of core task can lead to consideration of how users will undertake these tasks.

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Cut-down Psychological Theories as User Models

Model Human Processor (MHP) by Card, Moran and Newell 1983, one that can be used by designers and other computer scientists without the irrelevant complexities of a fully-

MHP (Model Human Processor) Concept

* photo credit: sja_engotzz

This model has always been criticized by a lot of Psychology experts due to the fact that it is not made for study theory but to solve common IT issues. However, it is perhaps true thatMHP is past its sell-by date. Although it still inspires new approaches and designs.

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Simplistic Psychological Theories as User Model

Simplistic Theories combines psychological theory with system design practice with easy to understand concept.It has two distinct features:o Defined formally, a simplistic theory is intended to provide a powerful conceptual framework within which complex theories and research findings can be located, ando It has the ability to be repackaged to provide an overall depiction that can be used by designers and practical computer scientists as a guide, without requiring them to becomepsychologists.We will focus on the Simplex Theory (Adams and Langdon, 2003) as representative of the current state of knowledge about user models.Simplistic One as a Simplistic TheoryConstructed as five zones or modules of cognition which are partially independent of each other. Each module possesses both memory and local processing capacity, each of which isacting as a von Neumann machine, allowing the overall system a level of parallel processing and autonomous self-diagnosis.Provides a simple, yet elegant, framework for the Interactive System designer or computer scientist to apply to the solution of real-world computing problems.

The Simplex One Theory with 5 components representing von Neumann's original model.

As a reference, here is the original von Neumann Computer Model.

User Models and Evaluation

Using Design Principles (Heuristics) for EvaluationDesign rules tend to give precise recommendations about specific design aspects, whereas design guidelines are low in authority and are more general in their application.-

Design rules are very prescriptive about specific areas of design.

Standards tend to be imposed by a regulatory body.

Hardware and software manufacturers produce commercial style guides and corporate style guides are developed by companies for their own internal use; it enhance usability of aproduct through consistency; the maintenance of look and feel across many product lines is observed.Guidelines are not prescriptive in the way that rules are, but it describes the usability concepts that help us judge designs, and gain a stronger understanding of usability as a concept.They tend to be based on more general usability principles; they cover a wide range of interface features and concepts. Lets now look at some of the well-known design principles:1.2.

Learnability we tend to learn system through understanding and generalizing about the system as a whole when we try new features.Predictability the user needs to be aware of all options that the system allows, and be able to work out which ones they will need for their desired action.

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Consistency the look and feel of the system should be consistent, it allows users to easily navigate and explore new features and systems.Flexibility it is in the way a user and the system exchange information in many ways.

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Recoverability a lot of users learn through exploration. It is vital that the system that can undo actions and let the user recover from their mistakes.Responsiveness it is the rate of communication between the system and a user.

Evaluating User Requirements with Simplex One

The main point of Simplex One is that each module can take input from any other module in the system via the executive function.1.2.

Perception (input) the ability to take in new information from the senses, to analyze and store information and to relate currently held information to it.Response (output) the ability to select, organize, time and implement appropriate responses.

3.4.

Abstract working memory to take, hold and process task-relevant memories while they are needed to support action.Long-term memory the warehouse of long-term memory, which stores the occurrence of key events and symbols.

a. Episodic memory you remember the scene, episode or situation you were in.b. Semantic memory this is a store of our world knowledge where we have not retained the context.Example: We ate at Mang Inasal last Monday.Episodic: They ate at Mang Inasal.Semantic: Mang Inasal has a delicious food. (You just know that the food there is delicious, without even realizing that you know it or where you got the idea).5. Executive Functions this is where information is switched between the foregoing four psychological modules of the theory, where consequences of such transfers areorganized, where the functions of the different modules are mediated and where task requirements are organized and monitored.

Normans 7 PrinciplesVisibility The more visible functions are, the more likely users will be able to know what to do next. Incontrast, when functions are "out of sight," it makes them more difficult tofind and know how to use.Feedback Feedback is about sending back information about what action has been done and what has been accomplished, allowing the person to continue with the activity.Various kinds of feedback are available for interaction design-audio, tactile, verbal, and combinations of these.Constraints The design concept of constraining refers to determining ways of restricting the kind of user interaction that can take place at a given moment. There are variousways this can be achieved.Mapping This refers to the relationship between controls and their effects in the world. Nearly all artifacts need some kind of mapping between controls and effects, whether it isa flashlight, car, power plant, or cockpit. An example of a good mapping between control and effect is the up and down arrows used to represent the up and down movement of thecursor, respectively, on a computer keyboard.Consistency This refers to designing interfaces to have similar operations and use similar elements for achieving similar tasks. In particular, a consistent interface is one thatfollows rules, such as using the same operation to select all objects. For example, a consistent operation is using the same input action to highlight any graphical object at theinterface, such as always clicking the left mouse button. Inconsistent interfaces, on the other hand, allow exceptions to a rule.Affordance is a term used to refer to an attribute of an object that allows people to know how to use it. For example, a mouse button invites pushing (in so doing acting clicking)by the way it is physically constrained in its plastic shell. At a very simple level, to afford means "to give a clue" (Norman, 1988). When the affordances of a physical object areperceptually obvious it is easy to know how to interact with it.

When all else fails, standardize

Shneiderman's "Eight Golden Rules of Interface Design"

These rules were obtained from the text Designing the User Interface by Ben Shneiderman. Shneiderman proposed this collection of principles that are derived heuristically fromexperience and applicable in most interactive systems after being properly refined, extended, and interpreted [9].To improve the usability of an application it is important to have awell designed interface. Shneiderman's "Eight Golden Rules of Interface Design" are a guide to good interaction design.1. Strive for consistency.Consistent sequences of actions should be required in similar situations; identical terminology should be used in prompts, menus, and help screens; and consistent commandsshould be employed throughout.2. Enable frequent users to use shortcuts.As the frequency of use increases, so do the user's desires to reduce the number of interactions and to increase the pace of interaction. Abbreviations, function keys, hiddencommands, and macro facilities are very helpful to an expert user.3 Offer informative feedback.For every operator action, there should be some system feedback. For frequent and minor actions, the response can be modest, while for infrequent and major actions, theresponse should be more substantial.4 Design dialog to yield closure.Sequences of actions should be organized into groups with a beginning, middle, and end. The informative feedback at the completion of a group of actions gives the operators thesatisfaction of accomplishment, a sense of relief, the signal to drop contingency plans and options from their minds, and an indication that the way is clear to prepare for the nextgroup of actions.5 Offer simple error handling.As much as possible, design the system so the user cannot make a serious error. If an error is made, the system should be able to detect the error and offer simple,comprehensible mechanisms for handling the error.6 Permit easy reversal of actions.This feature relieves anxiety, since the user knows that errors can be undone; it thus encourages exploration of unfamiliar options. The units of reversibility may be a single action,a data entry, or a complete group of actions.7 Support internal locus of control.Experienced operators strongly desire the sense that they are in charge of the system and that the system responds to their actions. Design the system to make users the initiatorsof actions rather than the responders.8 Reduce short-term memory load.The limitation of human information processing in short-term memory requires that displays be kept simple, multiple page displays be consolidated, window-motion frequency bereduced, and sufficient training time be allotted for codes, mnemonics, and sequences of actions.Heuristic EvualationThe word heuristic means search strategy. All principles, such as the ones described in the list that follows, can be used as heuristics. The search that they are used for potentialusability problems with a design. They cannot absolutely tell you specific things such as never use red text on a blue background. By contrast, the use of heuristics involves

making interpretations and judgments. The heuristic simply reminds you of the need to look for stuff. Heuristics are normally used as a checklist of things to look for: fromrelatively simple judgments (is there an undo facility?) to harder judgments about the way that the system is designed.We have a lot of design principles to be taken into account including Normans seven principles (1988), Schneidermans eight golden rules (1998), Tognazzinisinteraction design principles (1992) and Neilsens ten heuristics (2001).Here is the most recent proposed heuristics by Neilsen:1.2.3.4.5.6.7.8.9.10.

Visibility of System Status always keep the user informed about what is going on through providing appropriate feedback in a reasonable time.Match between system and real world speak the users language, using words, phrases and concepts, rather than system-oriented terms.User control and freedom provide ways of allowing users to easily escape from places they unexpectedly find themselves, by using clearly marked emergency exits.Consistency and standards avoid making users wonder if different words, situations or actions mean the same thing.Error prevention where possible, prevent errors occurring in the first place.Helping users recognize, diagnose and recover from errors use plain language to describe the nature of the problem and suggest some way of solving it.Recognition rather than recall make objects, actions and options visible.Flexibility and efficiency of use provide accelerators that are invisible to novice users, but allow more experienced users to carry out tasks more quickly.Aesthetic and minimalist design avoid using information that is irrelevant or rarely needed.Help and documentation provide information that can be easily searched and provides help in a set of concrete steps that can easily be followed.